Device and method for acquiring system information by decoding signals in wireless communication system

ABSTRACT

The present disclosure relates to a pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution (LTE). According to various embodiments, a device of a terminal, in a wireless communication system, can include at least one processor and at least one transceiver operatively coupled to the at least one processor. The at least one transceiver configured to receive, from a base station, a first signal transmitted using a first beam of the base station and including system information and receive, from the base station, a second signal transmitted using a second beam of the base station and including the system information, and the at least one processor is configured to decode the second signal in combination with the first signal, thereby enabling the system information to be acquired.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/979,022 filed on Sep. 8, 2020; which has issued as U.S. Pat. No.11,444,681 on Sep. 13, 2022, which is a U.S. National Stage applicationunder 35 U.S.C. § 371 of an International application numberPCT/KR2019/002665 filed on Mar. 7, 2019, which is based on and claimspriority of a Korean patent application number 10-2018-0026985 filed onMar. 7, 2018, in the Korean Intellectual Property Office, the entiredisclosure of each of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The disclosure generally relates to a wireless communication system and,more particularly, to a device and method for acquiring systeminformation in a wireless communication system.

BACKGROUND ART

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’.

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud RadioAccess Networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, Coordinated Multi-Points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, Hybrid FSK and QAM Modulation (FOAM) and slidingwindow superposition coding (SWSC) as an advanced coding modulation(ACM), and filter bank multi carrier (FBMC), non-orthogonal multipleaccess (NOMA), and sparse code multiple access (SCMA) as an advancedaccess technology have been developed.

For communication with a base station, it is essential for a terminal toacquire system information. To this end, the base station may broadcastsystem information periodically or upon request, and the terminal maydecode a signal including the system information. A failure to decodethe system information makes communication impossible, and a successrate of decoding the system information may thus have a great influenceon securing service coverage.

DISCLOSURE OF INVENTION Technical Problem

Based on the foregoing discussion, the disclosure provides a device andmethod for effectively acquiring system information in a wirelesscommunication system.

The disclosure provides the device and method for increasing a decodingsuccess rate of system information in the wireless communication system.

The disclosure provides the device and method for decoding signalsincluding system information transmitted via multiple beams in thewireless communication system.

The disclosure provides the device and method for determining beams fordecoding system information in the wireless communication system.

The disclosure provides the device and method for acquiring systeminformation by combining signals transmitted via different beams in thewireless communication system.

The disclosure provides the device and method for storing and managingchannel qualities for beams for decoding in the wireless communicationsystem.

Solution to Problem

According to various embodiments, in the wireless communication system,a terminal device may include at least one processor and at least onetransceiver operatively coupled to the at least one processor. The atleast one transceiver receives, from a base station, a first signalwhich is transmitted using a first beam of the base station and includessystem information, and receives, from the base station, a second signalwhich is transmitted using a second beam of the base station andincludes the system information, and the at least one processor decodesthe second signal in combination with the first signal, thereby enablingthe system information to be acquired.

According to various embodiments of the disclosure, an operation methodof a terminal in a wireless communication system may include: receivinga first signal, which is transmitted using a first beam of a basestation and includes system information, from the base station;receiving a second signal, which is transmitted using a second beam ofthe base station and includes the system information, from the basestation; and decoding the second signal by combining the first signal,thereby acquiring the system information.

Advantageous Effects of Invention

In the device and method according to various embodiments of thedisclosure, a probability of acquiring system information is increasedby combining and decoding signals transmitted using multiple beams.

In the device and method according to various embodiments of thedisclosure, a smooth communication environment can be maintained byincreasing a probability of success in decoding system information.

Effects obtainable from the disclosure may not be limited to theabove-mentioned effects, and other effects which are not mentioned maybe clearly understood, through the following descriptions, by thoseskilled in the art to which the disclosure pertains.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a wireless communication system according to variousembodiments of the disclosure;

FIG. 2 illustrates an example of a configuration of a base station inthe wireless communication system according to various embodiments ofthe disclosure;

FIG. 3 illustrates an example of the configuration of the base stationin the wireless communication system according to various embodiments ofthe disclosure;

FIG. 4A to FIG. 4C illustrate a configuration of a communication unit inthe wireless communication system according to various embodiments ofthe disclosure;

FIG. 5 illustrates an example of a beam-based combined decodingaccording to various embodiments of the disclosure;

FIG. 6A and FIG. 6B illustrate flowcharts of a terminal, for thebeam-based combined decoding according to various embodiments of thedisclosure;

FIG. 7 illustrates a flowchart of a terminal for determining a decodingbeam according to various embodiments of the disclosure;

FIG. 8 illustrates a flowchart of a terminal, for combining probabilityinformation according to various embodiments of the disclosure;

FIG. 9 illustrates a flowchart of a terminal, for acquiring systeminformation according to various embodiments of the disclosure;

FIG. 10 illustrates an example of acquiring system information accordingto various embodiments of the disclosure;

FIG. 11 illustrates a flowchart of a terminal, for managing beaminformation according to various embodiments of the disclosure;

FIG. 12 illustrates an example of managing beam information according tovarious embodiments of the disclosure; and

FIG. 13 illustrates an example of resource information related to a beamaccording to various embodiments of the disclosure.

BEST MODE FOR CARRYING OUT THE INVENTION

The terms used in the disclosure are only used to describe specificembodiments, and are not intended to limit the disclosure. A singularexpression may include a plural expression unless they are definitelydifferent in a context. Unless defined otherwise, all terms used herein,including technical and scientific terms, have the same meaning as thosecommonly understood by a person skilled in the art to which thedisclosure pertains. Such terms as those defined in a generally useddictionary may be interpreted to have the meanings equal to thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the disclosure. In some cases, even the term defined in thedisclosure should not be interpreted to exclude embodiments of thedisclosure.

Hereinafter, various embodiments of the disclosure will be describedbased on an approach of hardware. However, various embodiments of thedisclosure include a technology that uses both hardware and software,and thus the various embodiments of the disclosure may not exclude theperspective of software.

Hereinafter, the disclosure relates to a device and method for acquiringinformation essential for communication, which is system information, ina wireless communication system. Specifically, the disclosure describesa technique for acquiring system information by performing decoding bycombining signals transmitted using multiple beams in a wirelesscommunication system.

Terms referring to or related to system information (e.g., a physicalbroadcast channel (PBCH), an enhanced PBCH (ePBCH), an xPBCH, a masterinformation block (MIB), a system information block (SIB), and an xSIB),terms referring to a signal (e.g., a channel, a block, and a transportinstance), terms referring to a beam, terms related to resources (e.g.,a symbol, a slot, a half frame, and a frame), terms related toprobability (e.g., a prior probability, a posterior probability,likelihood, and a log likelihood ratio (LRR)), terms referring tonetwork entities, terms referring to elements of a device, and the like,which are used in the following description, are illustrated for theconvenience of description. Therefore, the disclosure is not limited tothe terms described below, and other terms having equivalent technicalmeanings may be used.

The disclosure describes various embodiments by using terms used in somecommunication specifications (e.g., 3rd generation partnership project(3GPP)), but this is merely illustrative. Various embodiments of thedisclosure may also be easily modified and applied to othercommunication systems.

FIG. 1 illustrates a wireless communication system according to variousembodiments of the disclosure. FIG. 1 illustrates a base station 110, aterminal 120, and a terminal 130, as a part of nodes using a wirelesschannel in a wireless communication system.

The base station 110 is a network infrastructure that provides wirelessaccess to the terminals 120 and 130. The base station 110 has coveragedefined as a predetermined geographic area on the basis of the distanceover which a signal may be transmitted. The base station 110 may bereferred to as, in addition to the base station, an “access point (AP)”,an “eNodeB (eNB)”, a “5th generation node (5G node)”, a “wirelesspoint”, or other terms having an equivalent technical meaning. Accordingto various embodiments, the base station 110 may be connected to one ormore “transmission/reception points (TRPs)”. The base station 110 maytransmit a downlink signal to or may receive an uplink signal from theterminal 120 or the terminal 130 via one or more TRPs.

Each of the terminal 120 and the terminal 130 is a device used by auser, and performs communication with the base station 110 via thewireless channel. In some cases, at least one of the terminal 120 andthe terminal 130 may be operated without involvement of a user. That is,at least one of the terminal 120 and the terminal 130 is a device thatperforms machine type communication (MTC) and may not be carried by auser. Each of the terminal 120 and the terminal 130 may be referred toas, in addition to a terminal, a “user equipment (UE)”, a “mobilestation”, a “subscriber station”, a “customer premises equipment (CPE)”,a “remote terminal”, a “wireless terminal”, an “electronic device”, a“user device”, or other terms having equivalent technical meaning.

The base station 110, the terminal 120, and the terminal 130 maytransmit and receive wireless signals in a millimeter wave band (e.g.,28 GHz, 30 GHz, 38 GHz, and 60 GHz). At this time, in order to improve achannel gain, the base station 110, the terminal 120, and the terminal130 may perform beamforming. The beamforming may include transmissionbeamforming and reception beamforming. That is, the base station 110,the terminal 120, and the terminal 130 may assign a directivity to atransmission signal or a reception signal. To this end, the base station110 and the terminals 120 and 130 may select serving beams 112, 113,121, and 131 via a beam search procedure or a beam management procedure.After the serving beams 112, 113, 121, and 131 are selected,communication may then be performed via resources that are in quasico-located (QCL) relationship with resources at which the serving beams112, 113, 121, and 131 are transmitted.

If large-scale characteristics of a channel, via which a symbol on afirst antenna port has been transferred, can be inferred from a channelvia which a symbol on a second antenna port has been transferred, it maybe estimated that the first antenna port and the second antenna port arein a QCL relationship. For example, the large-scale characteristics mayinclude at least one among a delay spread, a doppler spread, a dopplershift, an average gain, an average delay, and a spatial receiverparameter.

The terminal 120 may receive a signal including system information fromthe base station 110. The terminal 120 may receive system informationbefore connection (e.g., radio resource control (RRC) IDLE) to the basestation 110. The terminal 120 may receive system information even afterbeing connected to the base station 110 (e.g., RRC CONNECTED). Thesystem information may include information for generation andconfiguration of a connection to the base station 110 and informationfor configuration and controlling of an environment of communicationwith the base station.

The terminal 110 may transmit a signal including system information. Forexample, the base station 110 may broadcast a signal including systeminformation. The base station 110 may transmit a signal via a broadcastchannel (e.g., a PBCH). As another example, the base station 110 maybroadcast a signal including system information via a shared channel(e.g., a physical downlink shared channel (PDSCH)). The base station 110may periodically and repeatedly transmit a signal including systeminformation.

The base station 110 may perform beamforming to transmit systeminformation. The base station 110 may transmit each of signals includingsystem information by using a different beam. The base station 110 maytransmit signals via beam sweeping. The terminal 120 may acquire systeminformation by receiving signals transmitted using beamforming.Hereinafter, the disclosure describes a method for acquiringbeamforming-based system information.

FIG. 2 illustrates a configuration of a base station in the wirelesscommunication system according to various embodiments of the disclosure.The configuration illustrated in FIG. 2 may be understood as aconfiguration of the base station 110. The terms “-unit”, “-device”,etc. used hereinafter refer to a unit that processes at least onefunction or operation, which may be implemented by hardware or software,or a combination of hardware and software.

Referring to FIG. 2 , the base station 110 includes a wirelesscommunication unit 210, a backhaul communication unit 220, a storageunit 230, and a controller 240.

The wireless communication unit 210 performs functions to transmit orreceive a signal through a wireless channel. For example, thecommunication unit 210 performs conversion between a baseband signal anda bitstream according to a physical layer specification of a system. Forexample, when transmitting data, the wireless communication unit 210generates complex symbols by encoding and modulating a transmissionbitstream. When receiving data, the wireless communication unit 210restores a received bitstream by demodulating and decoding the basebandsignal. The wireless communication unit 210 up-converts the basebandsignal to a radio frequency (RF) band signal, transmits the up-convertedRF band signal via an antenna, and then down-converts the RF band signalreceived via the antenna to a baseband signal.

For example, the wireless communication unit 210 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a digital-to-analog converter (DAC), an analog-to-digitalconverter (ADC), and the like. Also, the wireless communication unit 210may include multiple transmission/reception paths. Furthermore, thewireless communication unit 210 may include at least one antenna arrayincluding multiple antenna elements. In terms of hardware, the wirelesscommunication unit 210 may include a digital unit and an analog unit,wherein the analog unit includes multiple sub-units according to anoperating power, an operating frequency, and the like.

The wireless communication unit 210 may transmit or receive a signal.For example, the wireless communication unit 210 may transmit asynchronization signal, a reference signal, system information, amessage, control information, data, or the like. The wirelesscommunication unit 210 may perform beamforming. In order to givedirectivity according to a configuration of the controller 240 to asignal to be transmitted or received, the wireless communication unit210 may apply a beamforming weight to the signal. The wirelesscommunication unit 210 may repeatedly transmit a signal while changing abeam that is formed.

The wireless communication unit 210 transmits and receives a signal asdescribed above. Accordingly, all or a part of the wirelesscommunication unit 210 may be referred to as “a transmitter”, “areceiver”, or “a transceiver”. In the following description,transmission and reception performed via a wireless channel are used ina sense including processing performed as described above by thewireless communication unit 210.

The backhaul communication unit 220 provides an interface that performscommunication with other nodes within a network. That is, the backhaulcommunication unit 220 converts, into a physical signal, a bitstreamtransmitted from the base station 110 to another node, for example,another access node, another base station, upper node, core network,etc., and converts a physical signal received from another node into abitstream.

The storage unit 230 stores data, such as configuration information, anapplication program, and a basic program for operations of the basestation 110. The storage unit 230 may include a volatile memory, anonvolatile memory, or a combination of a volatile memory and anonvolatile memory. The storage unit 230 provides stored data inresponse to a request of the controller 240.

The controller 240 controls overall operations of the base station 110.For example, the controller 240 transmits and receives a signal via thewireless communication unit 210 or the backhaul communication unit 220.Further, the controller 240 records and reads data in the storage unit230. The controller 240 may perform functions of a protocol stackrequired by the communication standard. To this end, the controller 240may include at least one processor. According to various embodiments,the controller 240 may control the base station 110 to performoperations described below based on various embodiments.

FIG. 3 illustrates a configuration of a terminal in the wirelesscommunication system according to various embodiments of the disclosure.The configuration illustrated in FIG. 3 may be understood as theconfiguration of the terminal 120. The terms “-unit”, “-device”, etc.used hereinafter refer to a unit that processes at least one function oroperation, which may be implemented by hardware or software, or acombination of hardware and software.

Referring to FIG. 3 , the terminal 120 includes a communication unit310, a storage unit 320, and a controller 330.

The communication unit 310 performs functions for transmitting orreceiving a signal via a wireless channel. For example, thecommunication unit 310 performs conversion between a baseband signal anda bitstream according to a physical layer specification of a system. Forexample, when transmitting data, the communication unit 310 generatescomplex symbols by encoding and modulating a transmission bitstream.When receiving data, the communication unit 310 restores a receivedbitstream by demodulating and decoding the baseband signal. Thecommunication unit 310 up-converts the baseband signal into an RF bandsignal, transmits the up-converted RF band signal via an antenna, andthen down-converts the RF band signal received via the antenna into abaseband signal. For example, the communication unit 310 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a DAC, an ADC, and the like.

Also, the communication unit 310 may include a plurality oftransmission/reception paths. Further, the communication unit 310 mayinclude at least one antenna array including multiple antenna elements.In terms of hardware, the communication unit 310 may include a digitalcircuit and an analog circuit (e.g., a radio frequency integratedcircuit (RFIC)). The digital circuit and the analog circuit may beimplemented in a single package. The communication unit 310 may includea plurality of RF chains. Further, the communication unit 310 mayperform beamforming. In order to give directivity according to aconfiguration of the controller 330 to a signal to be transmitted orreceived, the communication unit 310 may apply a beamforming weight tothe signal. According to an embodiment, the communication unit 310 mayinclude a radio frequency (RF) block. The RF block may include a firstRF circuitry associated with an antenna and a second RF circuitryassociated with baseband processing. The first RF circuitry may bereferred to as RF-A (antenna). The second RF circuitry may be referredto as RF-B (baseband).

Further, the communication unit 310 may transmit or receive a signal.The communication unit 310 may receive a downlink signal. The downlinksignal may include a synchronization signal (SS), a reference signal(RS) (e.g., demodulation (DM)-RS), system information (e.g., MIB, SIB,remaining system information (RMSI), and other system information(OSI)), a configuration message, control information, downlink data, orthe like. The communication unit 310 may transmit an uplink signal. Theuplink signal may include a random access-related signal (e.g., a randomaccess preamble (RAP) (or message 1 (Msg1)) and message 3 (Msg3)) or areference signal (e.g., a sounding reference signal (SRS) and a DM-RS).The communication unit 310 may include different communication modulesto process signals of different frequency bands. Furthermore, thecommunication unit 310 may include a plurality of communication modulesto support a plurality of different radio access technologies. Forexample, different wireless access technologies may include Bluetoothlow energy (BLE), wireless fidelity (Wi-Fi), Wi-Fi gigabyte (WiGig),cellular networks (e.g., long term evolution (LTE)), new radio (NR), andthe like. The different frequency bands may include a super highfrequency (SHF) (e.g., 2.5 Ghz and 5 Ghz) band and a millimeter wave(e.g., 38 GHz, 60 GHz, etc.) band.

The communication unit 310 transmits and receives a signal as describedabove. Accordingly, all or a part of the communication unit 310 may bereferred to as “a transmitter”, “a receiver”, or “a transceiver”. In thefollowing description, transmission and reception performed via awireless channel are used in a sense including processing performed asdescribed above by the wireless communication unit 310.

The storage unit 320 stores data, such as configuration information, anapplication program, and a basic program for operations of the terminal120. The storage unit 320 may include a volatile memory, a nonvolatilememory, or a combination of a volatile memory and a nonvolatile memory.The storage unit 320 provides stored data in response to a request ofthe controller 330. According to various embodiments, the storage unit320 may include beam information. The beam information may includeinformation on a beam of the base station. In some embodiments, whenreceiving a signal transmitted using a beam of the base station, thestorage 320 may store a measurement result of channel quality for thesignal. In some embodiments, the storage 320 may store information on abeam (hereinafter, a decoding beam) related to decoding performed toacquire system information from among beams of the base station. Theinformation on the decoding beam may include resource informationrelating to a position (e.g., a symbol, a slot, and a frame) of aresource of the decoding beam or probability information (e.g., LLR)related to the decoding beam. In some embodiments, the storage 320 maystore statistical information related to the beam (e.g., the number ofdecoding attempts and a decoding success frequency).

The controller 330 controls overall operations of the terminal 120. Forexample, the controller 330 transmits and receives a signal via thecommunication unit 310. Further, the controller 330 records and readsdata in the storage unit 320. The controller 330 may perform functionsof a protocol stack required by the communication standard. To this end,the controller 330 may include at least one processor or amicro-processor, or may be a part of a processor. A part of thecommunication unit 310 and controller 330 may be referred to as a CP.The controller 330 may include various modules for performingcommunication.

According to various embodiments, the controller 330 may include abeam-resource identification unit 331, a decoding beam determinationunit 333, a probability information combination unit 335, and a decoder337. The beam-resource identification unit 331 may identify a resourcein which a signal transmitted using a specific beam is located. Thedecoding beam determination unit 333 may determine beams for performingcombined-decoding, that is, decoding beams, according to variousembodiments. The probability information combination unit 335 maycombine probability information of signals transmitted using thedecoding beams, in order to perform combined-decoding according tovarious embodiments. The decoder 337 may perform decoding using acombined signal or combined probability information. Here, thebeam-resource identification unit 331, the decoding-beam determinationunit 333, the probability information combination unit 335, and thedecoder 337 are codes or a set of instructions stored in the storageunit 320, and may be instructions/codes at least temporarily residing inthe controller 330 or storage spaces storing the instructions/codes, ormay be a part of circuitry constituting the controller 330, or a modulefor performing a function of the controller 330. According to variousembodiments, the controller 330 may control the terminal to performoperations described below based on various embodiments.

The configuration of the terminal illustrated in FIG. 3 is merely anexample and is not limited to the configuration illustrated in FIG. 3 .That is, according to various embodiments, some elements may be added,deleted, or changed.

FIG. 4A to FIG. 4C illustrate a configuration of a communication unit inthe wireless communication system according to various embodiments ofthe disclosure. FIG. 4A to FIG. 4C illustrate an example of a detailedconfiguration of the wireless communication unit 210 of FIG. 2 or thecommunication unit 310 of FIG. 3 . Specifically, FIG. 4A to FIG. 4Cillustrate elements to perform beamforming, as a part of the wirelesscommunication unit 210 of FIG. 2 or the communication unit 310 of FIG. 3.

Referring to FIG. 4A, the wireless communication unit 210 or thecommunication unit 310 includes an encoding and modulation unit 402, adigital beamformer 404, a plurality of transmission paths 406-1 to406-N, and an analog beamformer 408.

The encoding and modulation unit 402 performs channel encoding. Forchannel encoding, at least one among a low density parity check (LDPC)code, a convolution code, a polar code may be used. The encoding andmodulation unit 402 generates modulation symbols by performingconstellation mapping.

The digital beamformer 404 performs beamforming on a digital signal(e.g., modulation symbols). To this end, the digital beamformer 404multiplies modulation symbols by beamforming weights. Here, thebeamforming weights are used to change a magnitude and phase of asignal, and may be referred to as “a precoding matrix”, “a precoder”, orthe like. The digital beamformer 404 outputs digital-beamformedmodulation symbols to the plurality of transmission paths 406-1 to406-N. According to a multiple input multiple output (MIMO) transmissiontechnique, the modulation symbols may be multiplexed or the samemodulation symbols may be provided to the plurality of transmissionpaths 406-1 to 406-N.

The plurality of transmission paths 406-1 to 406-N convertdigital-beamformed digital signals into analog-signals. To this end,each of the plurality of transmission paths 406-1 to 406-N may includean inverse fast Fourier transform (IFFT) calculator, a cyclic prefix(CP) insertion unit, a DAC, and an up-converter. The CP insertion unitis for an orthogonal frequency division multiplexing (OFDM) scheme, andmay be excluded when another physical layer scheme (e.g., a filter bankmulti-carrier (FBMC)) is applied. That is, the plurality of transmissionpaths 406-1 to 406-N provide independent signal processing processes toa plurality of streams generated via digital beamforming. However,depending on an implementation scheme, some elements of the plurality oftransmission paths 406-1 to 406-N may be used in common.

The analog beamformer 408 performs beamforming on an analog signal. Tothis end, the digital beamformer 404 multiplies analog signals bybeamforming weights. The beamforming weights are used to change amagnitude and a phase of a signal. Specifically, according to aconnection structure between the plurality of transmission paths 406-1to 406-N and antennas, the analog beamformer 408 may be configured asshown in FIG. 4B or FIG. 4C.

Referring to FIG. 4B, signals input to the analog beamformer 408 aretransmitted through the antennas via phase/magnitude conversion andamplification calculation. At this time, signals of respective paths aretransmitted through different antenna sets, i.e., antenna arrays.Referring to processing of signals input through a first path, thesignals are converted into signal sequences having differentphases/magnitudes or the same phase/magnitude by phase/magnitudeconverters 412-1-1 to 412-1-M, amplified by the amplifiers 414-1-1 to414-1-M, and then transmitted through the antennas.

Referring to FIG. 4C, signals input to the analog beamformer 408 aretransmitted through the antennas via phase/magnitude conversion andamplification calculation. At this time, signals of respective paths aretransmitted through the same antenna set, i.e., an antenna array.Referring to processing of signals input through the first path, thesignals are converted into signal sequences having differentphases/magnitudes or the same phase/magnitude by the phase/magnitudeconverters 412-1-1 to 412-1-M, and amplified by the amplifiers 414-1-1to 414-1-M. For transmission through a single antenna array, theamplified signals are combined by combination units 416-1-1 to 416-1-Mon the basis of antenna elements, and then transmitted through theantennas.

FIG. 4B shows an example in which an independent antenna array specificto each transmission path is used, and FIG. 4C shows an example in whichtransmission paths share one antenna array. However, according toanother embodiment, some transmission paths may use an independentarray, and the remaining paths may share one antenna array. Further,according to still another embodiment, a structure adaptively changeabledepending on a situation may be used by applying a structure switchablebetween transmission paths and antenna arrays.

In order for the terminal to communicate with the base station, it isrequired to acquire system information. In the system according tovarious embodiments, the base station may transmit signals includingsystem information by using different beams. The terminal may attemptdecoding at a time resource corresponding to a specific beam (e.g., abeam having a high channel quality).

When the terminal fails to acquire system information, that is, whendecoding by the terminal fails, the terminal may receive a signalincluding system information again and may attempt decoding. At thistime, waiting until the time resource corresponding to the specific beamand attempting decoding may be inefficient. Specifically, the time toacquire system information is delayed, and therefore it may cause adecrease in coverage or a decrease in link stability.

In order to solve the above-described problems, a terminal according tovarious embodiments performs decoding by combining signals transmittedusing different beams. The disclosure describes a method for increasingan acquisition rate of system information by performing decoding bycombining signals.

Beam-Based Combined Decoding

FIG. 5 illustrates an example of a beam-based combined decodingaccording to various embodiments of the disclosure. Beam-based combineddecoding refers to decoding performed by combining signals transmittedvia a beamforming system. Hereinafter, beam-based combined decoding maybe briefly referred to as combined decoding. In FIG. 5 , terms andpremised configurations required to describe the combined decoding ofthe disclosure are defined. However, the disclosure is not limited tothe terms defined in FIG. 5 , and other terms having equivalenttechnical meanings can be used. In FIG. 5 , a situation in which aterminal receives a signal transmitted from a base station is describedas an example in order to describe combined decoding. A base station maybe the base station 110 of FIG. 1 . A terminal may be the terminal 120of FIG. 1 .

Referring to FIG. 5 , the terminal 120 may communicate with the basestation 110. In order to perform communication with the base station110, the terminal 120 is required to receive necessary information fromthe base station 110. Essential information for communication betweenthe terminal and the base station may be referred to as systeminformation. That is, the terminal 120 may receive system informationfrom the base station 110 in order to establish or manage a connectionto the base station 110.

The system information may include various types of information.According to various embodiments, the system information may include anMIB or an SIB. The MIB may include parameters necessary for acquiringinformation on a cell or parameters that need to be frequentlytransmitted. For example, the MIB may include parameters necessary toacquire SIB1. The SIB may include information for accessing the cell andparameters necessary to operate within the cell. The SIB may be definedas SIBx, such as SIB1, SIB2, etc., according to a type thereof. Forexample, SIB1 may include information regarding availability andscheduling of other SIBs.

According to various embodiments, the system information may include anMIB or an xSIB. The MIB may be transmitted on a broadcast channeldefined as a PBCH (or xPBCH). The PBCH (or xPBCH) may refer to abroadcast channel in which beamforming is performed in each orthogonalfrequency division multiplexing (OFDM) symbol for the MIB. According toan embodiment, the MIB may be acquired via an SS/PBCH block. An SIB (orxSIB) may be transmitted on the PDSCH (or a broadcast channel defined asan ePBCH) or may be transmitted. The ePBCH may refer to a broadcastchannel in which beamforming is performed in each OFDM symbol for anxSIB. The xSIB may include information for accessing a cell. The xSIBmay include information relating to initial cell attachment and radioresource configuration.

In addition, various terms referring to system information may be used.For example, system information may be referred to as minimum systeminformation, remaining minimum system information (RMSI), other systeminformation (OSI), etc. in addition to an MIB and an SIB. That is, thedisclosure is not limited to only system information of a specificcommunication system. In addition, the system information may refer toparameters corresponding to some fields, such as an MIB, an SIB, and anxSIB. That is, the system information does not necessarily refer to onemessage block itself, but may also refer to specific parameters or someinformation in one message block.

The base station 110 transmits a signal including system information sothat the terminal 120 accesses a cell of the base station 110. The basestation 110 may broadcast a signal including system information so thatany terminal in the cell may have access thereto. System information maybe transmitted via a logical channel of a broadcast control channel(BCCH). For example, system information may be transmitted via atransmission channel of a broadcast channel (BCH). As another example,system information may be transmitted via a downlink-shared channel(DL-SCH).

Hereinafter, for the convenience of description, a signal includingsystem information is referred to as a “system control signal”. However,in addition to the system control signal, various terms may refer to asignal including system information. For example, a signal includingsystem information may be referred to as a broadcast signal. Forexample, a signal including system information may be referred to as anSS block. Here, the SS block may include a synchronization signal (e.g.,a primary synchronization signal (PSS) and a secondary synchronizationsignal (SSS)) and system information transmitted via a PBCH. The SSblock may be referred to as an SS/PBCH block. In addition to this, asignal including system information may be referred to as a systemsignal, a configuration signal, a cell control signal, a broadcastcontrol signal, and the like.

The base station 110 may perform beamforming. For example, the basestation 110 may form a first beam 511, a second beam 512, a third beam513, a fourth beam 514, a fifth beam 515, a sixth beam 516, and aseventh beam 517. The base station 110 may perform a beam search inorder to configure a smooth beamforming communication environment withthe terminal 120. A beam search is a procedure for finding a beam thatguarantees a smoothest channel, and terms, such as beam sweeping or beamtraining and beam management, may be used to have the same or similarmeaning. For example, the base station 110 may transmit a beamformingsignal by using each of the first beam 511, the second beam 512, thethird beam 513, the fourth beam 514, the fifth beam 515, the sixth beam516, and the seventh beam 517.

By using at least one of the first beam 511, the second beam 512, thethird beam 513, the fourth beam 514, the fifth beam 515, the sixth beam516, and the seventh beam 517, the base station 110 may performbeamforming on system control signals including system information. Thebase station 110 may transmit system control signals by using aplurality of beams, so as to allow any terminal in the cell of the basestation 110 to access the base station 110. The base station 110 maytransmit a system control signal to any terminal in cell coverage byusing a plurality of beams.

Accordingly, all terminals located on the cell of the base station 110may acquire system information corresponding to the same content. Forexample, all terminals may acquire the same system frame number (SFN).For example, all terminals may acquire information on the sametransmission period (e.g., an SS/PBCH occasion and a beam referencesignal (BRS) transmission period). For example, the terminals mayacquire information relating to other system information (e.g.,numerology).

The base station 110 may transmit system control signals in a timedivision manner. Hereinafter, in the disclosure, a period in whichsystem control signals are transmitted may be referred to as a broadcastperiod. The base station 110 may transmit system control signals in eachbroadcast period. In some embodiments, the broadcast period may have afixed value. For example, the broadcast period may be 1 ms. As anotherexample, the broadcast period may be 5 ms. In some other embodiments,the broadcast period may have a variable value. For example, thebroadcast period may be adaptively configured to be one value among 5ms, 10 ms, 20 ms, and the like. For example, the broadcast period may benotified based on system information or a configuration message.

According to various embodiments, the broadcast period of the disclosuremay include various transmission periods. For example, the broadcastperiod may include a BRS transmission period. As another example, thebroadcast period may include an ePBCH transmission period. For stillanother example, the broadcast period may include an SS burst. The SSburst may refer to one or more SS blocks. For still another example, thebroadcast period may include an SS burst set. The SS burst set may referto one or more SS bursts.

The base station 110 may transmit each of the system control signals byusing an individual beam for each time resource in a broadcast period.Hereinafter, the disclosure is described by referring to a time resourceas a system unit period in which a system control signal is transmitted.However, in addition to a system unit period, terms, such as a beamtraining transmission opportunity, a system information transmissionopportunity, and an SS block transmission occasion, may be used to referto a time resource at which a system control signal is transmitted.Here, the time resource may have various sizes according to a type of abroadcast period. For example, the time resource may be one OFDM symbol.As another example, the time resource may be a plurality of OFDM symbols(e.g., 4 OFDM symbols). The base station 110 transmits a system controlsignal by changing a beam for each system unit period. For example, thebase station 110 may sequentially transmit system control signals in atotal of 7 system unit periods by using the first beam 511, the secondbeam 512, the third beam 513, the fourth beam 514, the fifth beam 515,the sixth beam 516, and the seventh beam 517, respectively.

A broadcast period may periodically arrive. The base station 110 maytransmit system control signals via different beams in a broadcastperiod that arrives at a predetermined period. A periodicity of abroadcast period may be referred to as a broadcast periodicity. Forexample, the base station 110 may transmit system control signals eachtime a broadcast period arrives, by using the first beam 511, the secondbeam 512, the third beam 513, the fourth beam 514, the fifth beam 515,the sixth beam 516, and the seventh beam 517, respectively.

System control signals transmitted via different beams may include thesame system information. That is, after generating one system controlsignal, the base station 110 may repeatedly transmit the same systemcontrol signal by changing a beam to be used for transmission and aresource (e.g., a system unit period) allocated for the beam. In someembodiments, each of system control signals may include other additionalinformation for each beam or each system control signal, in addition tosystem information common between beams. For example, the additionalinformation may be an index of a system control signal. That is, evensystem control signals transmitted within the same broadcast period mayinclude different information (i.e., different values of the sameparameter). According to an embodiment, in order to acquire systeminformation common between beams via combined decoding, a terminal mayperform combined decoding by compensating for different additionalinformation. For example, a terminal may change a part corresponding toan index of a previously received system control signal to a partcorresponding to an index of a system control signal that is currentlybeing attempted to be decoded, and then may perform combined-decoding.

The terminal 120 may receive a system control signal from the basestation 110. The terminal 120 may distinguish, as a resource, systemcontrol signals transmitted via different beams. For example, in orderto specify a fourth received system control signal, the terminal 120 mayidentify a fourth system unit period in a broadcast period. According tovarious embodiments, the terminal 120 may manage resource information toidentify at least one of beams of the base station 110. According to anembodiment, a QCL relationship between signals corresponding to the samesystem resource period in different broadcast periods may beestablished.

The terminal 120 may determine channel qualities of signals receivedfrom the base station 110. The terminal 120 may determine a systemcontrol signal to be decoded, on the basis of the channel quality. Thisis because the better a channel condition, the higher a probability ofsuccessful decoding. The terminal 120 may determine a system controlsignal suitable for decoding according to a channel quality. That is,the terminal 120 may determine a beam suitable for decoding.Hereinafter, a beam suitable for decoding, that is, a beam used fortransmission of a system control signal to be decoded is referred to asa decoding beam. The terminal 120 may determine a decoding beam. Forexample, the terminal 120 may select the fifth beam 515 as a beam of achannel having the best channel state. In other words, the terminal 120may determine the fifth beam 515 as a decoding beam.

The terminal 120 may identify a system unit period corresponding to thedecoding beam. The terminal 120 may attempt to decode a system controlsignal in the identified system unit period. For example, the terminal120 may identify a fifth OFDM symbol corresponding to the fifth beam 515in the broadcast period. The terminal 120 may attempt decoding in thefifth OFDM symbol of a subsequent broadcast period. As another example,the terminal 120 may identify four symbols corresponding to an SS blockcorresponding to the fifth beam 515 in the broadcast period. A systemunit period corresponding to a decoding beam may be referred to asdecoding resource(s).

If decoding in a decoding resource fails, the terminal 120 may attemptdecoding again in another decoding resource. If the decoding beam isdetermined again in the subsequent broadcast period or if the decodingresource is identified again, a connection delay may be caused due to awaiting time. In order to reduce the delay, it is required to increase aprobability of acquiring system information in the broadcast period. Inorder to further increase the probability of acquiring systeminformation, the terminal 120 may perform decoding by combining aplurality of system control signals. The plurality of combined systemcontrol signals may be signals transmitted using different beams. Thatis, to acquire system information, the terminal 120 may combine systemcontrol signals transmitted via different beams.

The terminal 120 may determine signals to be combined. The terminal 120may determine beams corresponding to the signals to be combined. Thatis, the terminal 120 may determine decoding beams. According to variousembodiments, the terminal 120 may determine decoding beams on the basisof channel qualities. By performing decoding by combining at least twoof system control signals corresponding to decoding beams, the terminal120 may be able to increase a probability to acquire system information.For example, the terminal 120 may determine the first beam 511, thefourth beam 514, the fifth beam 515, and the sixth beam 516 as decodingbeams. The terminal 120 may perform decoding by combining at least twoof the first beam 511, the fourth beam 514, the fifth beam 515, and thesixth beam 516. The terminal 120 may acquire system information viabeam-based combined decoding.

In FIG. 5 , terms necessary for beam-based combined decoding aredefined, and terms and background operations of communication systemsare described. Hereinafter, operations of a terminal for beam-basedcombined decoding are described in FIG. 6A and FIG. 6B.

FIG. 6A illustrates a flowchart of a terminal, for beam-based combineddecoding according to various embodiments of the disclosure. FIG. 6Aillustrates an operation method of the terminal 120.

Referring to FIG. 6A, in operation 601, the terminal may receive a firstsignal that is transmitted using a first beam and includes systeminformation. The first beam may be one of beams formed in a basestation, that is, beams of the base station. The first signal may be asystem control signal. The base station may generate the first signalincluding system information, and the base station may assign, to thefirst signal, a first system unit period corresponding to the firstbeam. The base station may transmit the first signal by using the firstbeam in the first system unit period. Although not illustrated in FIG.6A, according to an embodiment, the terminal may decode the firstsignal.

In operation 603, the terminal may receive a second signal that istransmitted using a second beam and includes system information. Thesecond beam may be one of beams formed in the base station. The secondsignal may be a system control signal. According to various embodiments,the second beam may be a beam different from the first beam. The secondbeam may be a beam different from the first beam from among beams usedin a period in which signals including system information are repeatedlytransmitted via different beams. The base station may generate thesecond signal including the same system information as the first signalin operation 601. The base station may assign, to the second signal, asecond system unit period corresponding to the second beam. The basestation may transmit the second signal by using the second beam in thesecond system unit period. The second system unit period may be a seconddecoding resource.

In operation 605, the terminal may perform decoding by combining thefirst signal and the second signal. That is, the terminal may performcombined-decoding. As a result, the terminal may acquire systeminformation.

As described with reference to FIG. 6A, the terminal may performcombined decoding on system control signals transmitted via differentbeams. The terminal may combine the system control signals, that is, thefirst signal and the second signal. In the disclosure, signals may becombined in various forms. For example, the combination between signalsmay be a combination of information related to each signal (e.g.,probability information and statistical information), as well as acombination of signals themselves. In some embodiments, the terminal mayperform decoding by combining probability information relating to thesecond signal and probability information relating to the first signalacquired when decoding the first signal. For example, the terminal mayperform decoding by adding bit-specific LLR values of the first signaland the second signal, respectively. In some other embodiments, theterminal may acquire a symbol by combining the first signal and thesecond signal before demodulation. For example, the terminal may acquirea symbol on the basis of phases or amplitudes of the first signal andthe second signal, respectively.

FIG. 6B illustrates a flowchart of a terminal, for beam-based combineddecoding according to various embodiments of the disclosure. FIG. 6Billustrates an operation method of the terminal 120. According tovarious embodiments, the terminal may determine whether a condition forperforming combined decoding is satisfied. Accordingly, the terminal mayperform combined decoding if the condition is satisfied. FIG. 6Billustrates beam-based combined decoding according to whether thecondition is satisfied.

Referring to FIG. 6B, in operation 611, the terminal may receive a firstsignal that is transmitted using a first beam and includes systeminformation. Operation 611 corresponds to operation 601 of FIG. 6A, andtherefore a detailed description of an overlapping configuration isomitted.

In operation 613, the terminal may receive a second signal that istransmitted using a second beam and includes system information.Operation 613 corresponds to operation 603 of FIG. 6B, and therefore adetailed description of an overlapping configuration is omitted.

In operation 615, the terminal may determine whether decoding of thefirst signal fails. That is, the terminal may determine whether systeminformation is acquired, via decoding of the first signal. If thedecoding of the first signal fails, the terminal may perform operation617. If the decoding of the first signal is successful, the terminal mayend decoding. That is, the terminal may not perform additional decodingin other decoding resources. The terminal may acquire system informationwhen decoding of the first signal is successful.

In operation 617, the terminal may perform decoding by combining thefirst signal and the second signal. That is, when decoding of the firstsignal fails, the terminal may attempt combined decoding to acquiresystem information. The terminal may decode the second signal bycombining the first signal. Instead of decoding the second signal, theterminal may perform decoding by combining the first signal and thesecond signal.

In FIG. 6B, a failure of decoding the first signal is described as acondition of combined decoding, but the disclosure is not limitedthereto. Another decoding condition may be used instead of a failure ofdecoding the first signal. For example, if a channel quality for thefirst signal is lower than a threshold, the terminal may attemptcombined decoding. Additional decoding conditions may be used inaddition to a failure of decoding the first signal. For example, ifdecoding of the first signal fails, the terminal may decode the secondsignal. If decoding of the second signal also fails, the terminal mayattempt combined decoding to acquire system information. After decodingof the second signal fails, the terminal may perform decoding bycombining the first signal and the second signal.

FIG. 6A and FIG. 6B illustrate a combination of two signals, but thedisclosure is not limited thereto. For combined decoding, more than twosignals may be combined. For example, the terminal may combine threedecoding beams. If decoding performed in two decoding resources fails,the terminal may perform decoding by combining a third system controlsignal with other system control signals in a decoding resource locatedat a last time point in time.

The terminal may acquire system information via combined decoding. Ifthe terminal combines and decodes signals instead of decoding only asingle signal, the terminal may successfully acquire system informationwith a higher probability. The terminal may access a cell via theacquired system information or may configure parameters for the cell.

Although not illustrated in FIG. 6A and FIG. 6B, the terminal maytransmit feedback information indicating an optimal beam to the basestation. A beam at a point of time when the system information isacquired may be different from a beam indicated by the feedbackinformation. This is because, when combined decoding is performed, theterminal may not necessarily acquire the system information in aresource corresponding to a beam having a highest channel quality.According to various embodiments, a beam for feedback information and abeam for decoding performed when the system information is acquired maybe different. Since a beam may be fed back and identified in the form(e.g., an SSB resource indicator (SSBRI) and a CRS resource indicator(CRI)) of a resource indicator, a difference between a resourceindicated by the feedback information and a resource in which successfuldecoding has been attempted is identified, so that it may be determinedwhether combined-decoding according to the disclosure is performed. Onthe other hand, since system information may be acquired via combineddecoding in a resource corresponding to a beam having an optimal channelquality, even if the beam of the feedback information and the beamrelated to system information acquisition are the same, it is consideredthat combined decoding of the disclosure is performed.

In FIG. 6A and FIG. 6B, operations of the terminal for combined decodingare described. If decoding is performed by combining arbitrary signals,decoding performance may be deteriorated. For example, if decoding isperformed by combining a signal having a low channel quality and anothersignal, which include the same system information, the systeminformation may be more distorted due to the signal having a low channelquality, and thus decoding may fail. Therefore, in order to performcombined decoding, the terminal is required to determine signals to becombined and decoded. That is, the terminal may determine decodingbeams. Hereinafter, in FIG. 7 , various schemes for determining decodingbeams are described.

Decoding Beam

FIG. 7 illustrates a flowchart of a terminal for determining a decodingbeam according to various embodiments of the disclosure. FIG. 7illustrates an operation method of the terminal 120. The terminal maydetermine decoding beams before performing the combined decoding of FIG.6A and FIG. 6B. The decoding beams refer to beams corresponding tosignals that are combined for combined decoding. The first beam and thesecond beam of the base station of FIG. 6A and FIG. 6B may be decodingbeams of FIG. 7 .

Referring to FIG. 7 , in operation 701, the terminal may receive signalstransmitted using a plurality of beams. The plurality of beams may be aplurality of beams formed in the base station. The base station maytransmit signals by using the plurality of beams. According to variousembodiments, in order to determine the decoding beams, the terminal mayreceive signals. In some embodiments, the terminal may receive systemcontrol signals including system information. For example, a systemcontrol signal may be an SS block including a synchronization signal.For example, the terminal may receive a plurality of SS blockstransmitted using a plurality of beams of the base station. In someother embodiments, the terminal may receive reference signalstransmitted using a plurality of beams. For example, the referencesignal may be at least one among a BRS, a beam refinement referencesignal (BRRS), a cell-specific reference signal (CRS), a channel stateinformation-reference signal (CSI-RS), and a demodulation-referencesignal (DM-RS). For example, the terminal may receive a plurality ofCSI-RSs transmitted using the plurality of beams of the base station. Asanother example, the terminal may receive DM-RSs transmitted using theplurality of beams of the base station.

In operation 703, the terminal may determine decoding beams. Forexample, the terminal may determine decoding beams on the basis of atleast one of a channel quality and a correlation between beams.Specifically, the terminal may perform measurement on each of thesignals received in operation 701, and may determine channel qualitiesor correlations between beams for the respective beams of the basestation from a measurement result.

A channel quality of the disclosure may be at least one of a beamreference signal received power (BRSRP), a reference signal receivedpower (RSRP), a reference signal received quality (RSRQ), a receivedsignal strength indicator (RSRI), a signal to interference and noiseratio (SINR), a carrier to interference and noise ratio (CINR), a signalto noise ratio (SNR), an error vector magnitude (EVM), a bit error rate(BER), and a block error rate (BLER). In addition to the above describedexamples, other terms having equivalent technical meanings or othermetrics indicating a channel quality may be used. Hereinafter, in thedisclosure, a high channel quality refers to a case in which a channelquality value related to a signal size is large or an error rate-relatedchannel quality value is small. A higher channel quality may mean that asmooth wireless communication environment is guaranteed. An optimal beammay refer to a beam having a highest channel quality among beams.

According to various embodiments, the terminal may determine decodingbeams on the basis of channel qualities. In some embodiments, theterminal may determine, as decoding beams, beams of the base stationwhich correspond to upper M (M is an integer of 2 or larger) channelqualities among the channel qualities. In some other embodiments, theterminal may determine decoding beams by using a channel qualitythreshold value. The terminal may compare channel qualities and channelquality threshold values for the respective beams of the base station.The terminal may determine, as a decoding beam, a beam of the basestation, which corresponds to a channel quality higher than the channelquality threshold value.

According to various embodiments, the terminal may determine decodingbeams on the basis of channel qualities and correlations between beams.Here, the correlation may be a metric indicating similarity ofdirections between beams. The reason for considering the correlation isthat, if radio paths formed by two beams are similar, when decoding of asystem control signal transmitted using one beam fails, decoding of asystem control signal transmitted using another beam is also more likelyto fail. When the correlation between the two beams has a value smallerthan or equal to a threshold value, the two beams may form independentpaths. The terminal may acquire the system information more easily bydecoding system control signals transmitted via various independentpaths. Hereinafter, the disclosure describes decoding of system controlsignals corresponding to beams having a low correlation, but is notlimited thereto. It is needless to say that according to an embodiment,the terminal may determine, as decoding beams, beams having a highcorrelation. By determining, as decoding beams, beams having a highcorrelation, a success probability of decoding may be increased whileminimizing burden on a receiver of the terminal.

The correlation between beams may be determined in a variety of ways.For example, the terminal may measure signals transmitted using beams.The terminal may determine a correlation between beams on the basis ofmeasurement information (e.g., a reception strength, an interference,and an error rate) for each beam. When a difference between measurementinformation for beams is smaller, the terminal may determine that acorrelation between the beams is high. For another example, the terminalmay determine a correlation between beams on the basis of angles ofarrival (AoA) of signals transmitted using the beams. When a differencebetween AoAs, is greater, a probability that signals are transmitted viadifferent physical paths is high, so the terminal may determine that acorrelation between the beams is low. For another example, the terminalmay determine a correlation between beams according to a distance of aresource index corresponding to each of the beams. For example, theterminal may determine that the correlation between the beams is lowerwhen a difference of the resource index between a specific beam andanother beam is greater. Here, a situation, in which the base stationsequentially performs beam sweeping in accordance with physicaldirections of the beams of the base station, is assumed.

In some embodiments, the terminal may determine decoding candidate beamsby using channel qualities and may determine decoding beams from amongthe decoding candidate beams on the basis of correlations between thebeams. Specifically, the terminal may determine, as the decodingcandidate beams, beams corresponding to a channel quality higher thanthe channel quality threshold value. The terminal may determine acombination of beams having a cross-correlation greater than or equal toa correlation threshold value from among the decoding candidate beams.The terminal may determine the determined combination of beams asdecoding beams. The number of beams in the combination may correspond tothe number of decoding beams configured to the terminal. If the numberof beams is 3 or more, it may be required that correlations between allthe beams are greater than or equal to the correlation threshold value.

In some embodiments, the terminal may identify a beam having a highestchannel quality, that is, an optimal beam, and may determine, asdecoding beams, beams having a correlation with the optimal beam, whichis less than the correlation threshold value, from among the remainingbeams of the base station, or may determine, as the decoding beams,upper M (M is an integer of 1 or more) beams having a low correlation.M+1 may correspond to the number of decoding beams configured to theterminal. The terminal may also determine the optimal beam as a decodingbeam.

According to various embodiments, the terminal may determine decodingbeams on the basis of reception beams of the terminal. The terminal maymeasure a plurality of signals transmitted from the base station. Theplurality of signals are transmitted using beams of the base station,i.e., transmission beams. The terminal may receive a plurality ofsignals by using one of the reception beams of the terminal, and mayreceive a plurality of signals by using another reception beam. Theterminal may measure channel qualities of beam pairs between thetransmission beams of the base station and the reception beams of theterminal, respectively, via reception beam sweeping.

The terminal may determine an optimal beam pair (a transmissionbeam-reception beam combination) corresponding to each of thetransmission beams of the base station. The terminal may determinetransmission beams corresponding to the same reception beam, as thedecoding candidate beams or the decoding beams. When the number ofdecoding beams is configured, the terminal may identify the decodingbeams among the decoding candidate beams. As such, the terminal mayreceive system control signals transmitted via decoding beams, by usingthe same reception beam. By using the same reception beam, the terminaldoes not need to change a separate RF configuration, and therefore aprocedure complexity of the terminal may be reduced.

According to various embodiments, the terminal may configure the numberof decoding beams. The terminal may identify as many as decoding beamsas the configured number. The terminal may determine the number ofdecoding beams. In some embodiments, the terminal may determine thenumber of decoding beams on the basis of information on the channelqualities determined in operation 701. For example, the terminal maydetermine the number of decoding beams according to the size of anaverage value of channel qualities. The terminal may increase the numberof decoding beams when overall RSRP values are low, that is, an RSRPaverage value is low. This is to increase a decoding gain by combiningmore signals. In some other embodiments, the terminal may determine thenumber of decoding beams to be a fixed number. Here, the fixed number isa preconfigured value and may be determined according to a capability ofthe terminal. For combined decoding, since multiple pieces of channelquality information need to be stored and a combined calculation thereofneeds to be performed, additional complexities may be required. Forexample, the terminal may determine the number of decoding beams to befour.

FIG. 7 describes terminal operations for determining decoding beamsbefore the terminal receives system control signals. However, thedisclosure is not limited thereto. According to an embodiment, theterminal may receive each of system control signals in a broadcastperiod and may determine decoding beams in the same broadcast period.The terminal may determine decoding beams within the broadcast periodafter first single decoding has failed.

In FIG. 7 , terminal operations for determining decoding beams forcombined decoding are described. Not only combining and decoding systemcontrol signals transmitted using decoding beams, that is, combineddecoding, but also determining decoding beams and succeeding in decodingof a first signal so as to access a cell without further combineddecoding, by the terminal, may also be understood as an embodiment ofthe disclosure. Hereinafter, FIG. 8 describes an example of a method forcombining system control signals corresponding to determined decodingbeams.

Combining

FIG. 8 illustrates a flowchart of a terminal, for combining probabilityinformation according to various embodiments of the disclosure. Aterminal illustrates the terminal 120 of FIG. 1 . As shown in operation605 of FIG. 6A, the terminal may perform decoding by combining systemcontrol signals after receiving the system control signals. Hereinafter,in FIG. 8 , embodiments of acquiring probability information for each ofsystem control signals, and then combining and decoding the probabilityinformation are described. The probability information may beprobability information for a system control signal.

The probability information may include an indicator relating to whethera bit, a symbol, a codeword, etc. of a system control signal have aspecific value or specific values. For example, the probabilityinformation may include a log likelihood ratio (LRR). The probabilityinformation may include an LLR value indicating whether each of bitsconstituting a system control signal is 1.

Referring to FIG. 8 , in operation 801, the terminal may determine firstprobability information for system information of a first signal. Thefirst signal including system information may be a first system controlsignal. The terminal may detect bits or symbols of the first systemcontrol signal and may determine first probability information accordingto a detection result. Hereinafter, a situation in which the probabilityinformation includes an LLR value is described as an example. Theterminal may determine a first vector for the first system controlsignal in response to reception of the first system control signal. Theterminal may identify at least one candidate vector among multipleestimated vectors according to Euclidean distance (ED) calculation ofthe first vector and each of the multiple estimated vectors. Theterminal may calculate first LLR values corresponding to respective bitsof system information on the basis of at least one candidate vector. Forexample, each LLR value may be expressed as follows.

$\begin{matrix}{{{LLR}\left( b_{i} \right)} = {\log\frac{P\left( {b_{i} = 1} \right)}{P\left( {b_{i} = 0} \right)}}} & {{Equation}1}\end{matrix}$

b_(i) may indicate an i-th bit. LLR(b_(i)) may be an LLR valueindicating whether the i-th bit is 1. P(b_(i)=1) means a probabilitythat the i-th bit is “1”, and P(b_(i)=0) means a probability that thei-th bit is “0”.

The terminal may determine the first probability information includingthe first LLR values.

In operation 803, the terminal may determine second probabilityinformation for system information of a second signal. The second signalincluding system information may be a second system control signal. Theterminal may detect bits or symbols of the second system control signalin the same manner as the first system control signal, and may determinethe second probability information according to a detection result. Asan example, the terminal may determine second LLR values for the secondsystem control signal. The terminal may determine the second probabilityinformation including the second LLR values.

In operation 805, the terminal may combine the first probabilityinformation and the second probability information, so as to determinecombined probability information for system information. The terminalmay combine the first probability information and the second probabilityinformation. The first system control signal and the second systemcontrol signal may include the same system information. That is, thefirst probability information for the first system control signal andthe second probability information for the second system control signalrefer to probability information for the same content. For example, thefirst probability information may include first LLR values of bits ofthe first system control signal. The second probability information mayinclude second LLR values of bits of the second system control signal.Since the first system control signal and the second system controlsignal are modulated in the same manner (e.g., quadrature phase shiftkeying (QPSK)) and include the same system information, parameters orfields constituting the system information may correspond to the samebit position.

Depending on a detection result, at the same bit position, bit valuesmay differ. The terminal may determine combined probability informationfor a corresponding bit or symbol by combining the first probabilityinformation and the second probability information at a specific bit orsymbol position. For example, if the first probability information andthe second probability information include LLR values, the terminal maydetermine a combined LLR value of the i-th bit by adding a first LLRvalue of the i-th bit and a second LLR value of the i-th bit. Thecombined probability information may include combined LLR values forbits of the system information.

When the terminal combines the first probability information and thesecond probability information, a different weight may be applied toeach piece of probability information. The terminal may determine thecombined probability information by applying the first probabilityinformation and a first weight and applying a second weight to thesecond probability information. In some embodiments, the first weightand the second weight may be determined based on a channel quality. Forexample, if a channel quality of the first system control signal ishigher than a channel quality of the second system control signal, theterminal may configure the first weight to be greater than the secondweight. As another example, the terminal may determine the first weightand the second weight on the basis of the channel quality for the beamsinstead of the channel quality of system control signals. The terminalmay determine the first weight and the second weight on the basis ofinformation on the channel quality for each beam used to determinedecoding beams.

In some embodiments, if each of the system control signals shares thesame system information and further includes some other parameters(e.g., an index of the system control signal), the terminal may performcombined decoding by compensating for different parts and combining thesystem control signals. The terminal may acquire system information byperforming combined decoding.

In operation 807, the terminal may perform decoding based on thecombined probability information. The terminal may acquire a decodingresult based on the combined probability information. For example, theterminal may acquire the decoding result by performing determinationaccording to the combined LLR values. If decoding is successful, theterminal may acquire system information. If the system information isacquired, even if there is a remaining decoding resource in whichdecoding has not been attempted, the terminal may no longer perform adecoding attempt.

FIG. 8 describes that two pieces of probability information arecombined, but the disclosure is not limited thereto. It is needless tosay that the terminal may combine three or more pieces of probabilityinformation. In some embodiments, the terminal may sequentially increasethe number of combined signals up to a total number of decoding beamseach time when a system unit period arrives. If the number of decodingbeams is 3 or more, the terminal may combine 3 or more pieces ofprobability information. In some other embodiments, the number ofsignals to be combined may be configured within a fixed number. Eachtime when a system unit period arrives, the terminal may combineprobability information within a fixed number (e.g., 3). For example,the number of pieces of probability information to be combined may bedetermined according to a capability of the terminal.

In FIG. 8 , embodiments for combining probability information have beendescribed, but combining signals themselves in addition to probabilityinformation may also be considered. The terminal may directly combinesystem control signals before detecting symbols or bits of each systemcontrol signal. The terminal may detect symbols or bits from a combinedsignal and may perform decoding according to a detection result. Forexample, a modulation scheme of the system control signals may be QPSK.The terminal may acquire a combined signal by combining phaseinformation of the first system control signal and phase information ofthe second control signal.

It is needless to say that weights between signals may be differentlyapplied when the signals are directly combined, just as the weightsbetween the signals are differently applied when probability informationis combined. According to various embodiments, the terminal may performdecoding by applying the first weight to the first signal and the secondweight to the second signal. The first weight and the second weight maybe determined based on the channel quality for the first signal and thechannel quality for the second signal.

FIG. 9 illustrates a flowchart of a terminal, for acquiring systeminformation according to various embodiments of the disclosure. Aterminal illustrates the terminal 120 of FIG. 1 .

Referring to FIG. 9 , in operation 901, the terminal may determinedecoding beams. A decoding beam may be a beam corresponding to a signaldecoded by the terminal from among beams of the base station. Accordingto various embodiments, the terminal may determine decoding beams on thebasis of channel qualities. For example, the terminal may determine aBRSRP by measuring a BRS transmitted via different beams. The terminalmay determine upper M number of beams having a large BRSRP, as decodingbeams. As another example, the terminal may determine an SS block RSRPby measuring an SS block transmitted via different beams. The terminalmay determine upper M number of beams having a large SS block RSRP, asdecoding beams.

In operation 903, the terminal may determine decoding resources. Theterminal may identify system unit periods corresponding to decodingbeams from a broadcast period(s). The terminal may determine system unitperiods corresponding to decoding beams, as decoding resources. Forexample, the terminal may calculate and store a position of a symbol towhich a decoding beam is assigned. As another example, the terminal maycalculate and store positions of symbols to which a decoding beam isassigned or a position in a slot to which the decoding beam is assigned.

In operation 905, the terminal may determine whether or not a decodingperiod has arrived. The decoding period refers to a period in which theterminal performs decoding from among broadcast periods. For example,the terminal may determine, as a decoding period, a broadcast period inwhich an optimal terminal beam is scheduled during beam tracking. Thedecoding period may be determined to be not only one broadcast period,but also a plurality of broadcast periods, or may be determined to be apart of the broadcast periods.

If a subsequent broadcast period is not a decoding period, operation 901may be performed again. The terminal may update the decoding beams bymeasuring signals in the broadcast period. Unlike the description inFIG. 9 , the terminal may wait until a decoding period arrives. If thesubsequent broadcast period is a decoding period, the terminal mayperform operation 907. For example, the terminal may determine whetherdecoding resources calculated in an MIB/SIB subframe exist.

In operation 907, the terminal may identify decoding resources. Amongthe decoding resources determined in operation 903, the terminal mayidentify a decoding resource in which decoding has not been attempted.If first decoding is performed in the decoding period, the terminal mayidentify a decoding resource that is temporally advanced from among thedecoding resources. For example, if the decoding resource is a 3rdsymbol, a 5th symbol, and a 9th symbol among 14 symbols, the terminalmay identify the 3rd symbol as the decoding resource. If decoding is notfirst decoding in the decoding period, the terminal may determineremaining decoding resources, in which decoding has not been attempted,from among the decoding resources. The terminal may identify atemporally preceding decoding resource among the remaining decodingresources. That is, if operation 907 is performed after operation 915,the terminal may identify a decoding resource that arrives first in timefrom among the remaining decoding resources. For example, in a situationwhere the decoding resources are the 3rd symbol, the 5th symbol, and the9th symbol among 14 symbols, if an attempt to decode in the 3rd symbolthat is a first decoding resource fails, the terminal may identify thefifth symbol as a decoding resource.

In operation 909, the terminal may perform decoding. The terminal mayattempt decoding in the decoding resource. The terminal may receive thesystem control signal from the decoding resource identified in operation907. The terminal may attempt to decode the system control signal on thedecoding resource.

According to various embodiments, the terminal may perform singledecoding. Single decoding refers to decoding performed withoutcombination between system control signals. For example, the terminalmay perform single decoding in the case of first decoding in thedecoding period. In a situation where the decoding resources are the 3rdsymbol, the 5th symbol, and the 9th symbol among 14 symbols of thedecoding period, the terminal may attempt decoding in the 3rd symbolwithin the decoding period. As another example, the terminal may performsingle decoding even if it is not first decoding in the decoding period.The terminal may perform single decoding at each decoding attemptrepeated on a decoding resource.

According to various embodiments, the terminal may perform combineddecoding. Combined decoding refers to decoding performed via acombination between system control signals. Here, the combination mayinclude not only a combination of information (e.g., a signal detectionresult, probability information, or statistical information) related tosignals but also a combination of physical signals. The terminal mayincrease a decoding success probability by combining signals. That is,the terminal may increase a probability of acquiring system informationby performing combined decoding. For example, the terminal may performcombined decoding by performing LLR combining between system controlsignals transmitted via respective beams.

If it is not first decoding in the decoding period, the terminal mayperform combined decoding. For example, if previously attempted decodinghas failed, the terminal may perform combined decoding based on a systemcontrol signal in a currently identified decoding resource andpreviously failed decoding results. If decoding in the third symbol thatis the decoding resource has failed, decoding may be attempted bycombining the system control signal transmitted in the third symbol andthe system control signal transmitted in the fifth symbol. As anotherexample, if the previously attempted decoding and the decoding in thecurrently identified decoding resource have failed, the terminal maycombine the failed decoding results to perform combined decoding. Ifdecoding in the third and fifth symbols that are decoding resources hasfailed, decoding may be attempted by combining the system control signaltransmitted in the third symbol and the system control signaltransmitted in the fifth symbol.

According to an embodiment, even if it is not first decoding in thedecoding period, if there is prior information (e.g., informationacquired in the previous broadcast period) relating to the systeminformation, the terminal may combine the prior information withinformation related to the first system control signal so as to performcombined decoding.

In operation 911, the terminal may determine whether decoding issuccessful. The success or failure of decoding may be determined basedon a cyclic redundancy check (CRC) test. If decoding is successful, theterminal may perform operation 913. If decoding fails, the terminal mayperform operation 915.

In operation 913, the terminal may acquire the system information.Accordingly, even if there are remaining decoding resources, theterminal may not make an additional decoding attempt in the decodingresources.

In operation 915, the terminal may determine whether decoding has beenattempted in all decoding resources. If a decoding attempt is not madein all decoding resources, the terminal may perform operation 907 again.That is, the terminal may perform operation 907 if there is a decodingresource (hereinafter, a remaining decoding resource) in which adecoding attempt has not been made from among the decoding resources. Ifa decoding attempt has been made in all decoding resources, the terminalmay perform operation 917.

In operation 917, the terminal may determine a decoding failure. Ifdecoding has failed, the terminal may end system information acquisitionprocedures. Thereafter, the terminal may repeat procedures in operations911 to 917. The terminal may repeatedly attempt decoding to acquire thesystem information.

FIG. 10 illustrates an example of acquiring system information accordingto various embodiments of the disclosure. A base station may transmit asystem control signal including system information by using a beam. InFIG. 10 , a situation, in which a terminal sweeps beams of the terminalfor beam tracking, is described as an example. The terminal may change abeam of the terminal for each frame, and may receive system controlsignals by using the respective beams of the terminal. The beam of theterminal may be a downlink reception beam. The base station may change abeam of the base station within a frame, and may transmit system controlsignals by using respective beams of the base station. The beam of thebase station may be a downlink transmission beam.

Referring to FIG. 10 , a timing diagram 1010 shows a time flow of thebase station. The timing diagram 1020 shows the time flow of the basestation. In the timing diagram 1010 and a timing diagram 1020, the samepoint on the vertical axis refers to the same time point.

The terminal may receive a signal by using beam #2 of the terminal in afirst frame 1021. A frame number of the first frame 1021, that is, asystem frame number (SFN), may be SFN #0. The terminal may receive asignal by using beam #1 of the terminal in a second frame 1022. A framenumber of the second frame 1022 may be SFN #1. The terminal may receivea signal by using beam #0 of the terminal in a third frame 1023. A framenumber of the third frame 1023 may be SFN #2.

The base station may transmit system control signals in a firstbroadcast period 1011. The base station may transmit a system controlsignal via different beams of the base station. Like in the firstbroadcast period 1011, the base station may transmit a system controlsignal in a second broadcast period 1012, a third broadcast period 1013,a fourth broadcast period 1014, and a fifth broadcast period 1015. In anexample shown in FIG. 10 , each broadcast period may be a 0th subframeor a 25th subframe in a frame. That is, the first broadcast period 1011may be subframe number (SBFN) #0 of SFN #0. The second broadcast period1012 may be subframe number (SBFN) #25 of SFN #0. The third broadcastperiod 1013 may be subframe number (SBFN) #0 of SFN #1. The fourthbroadcast period 1014 may be subframe number (SBFN) #25 of SFN #1. Thefifth broadcast period 1015 may be subframe number (SBFN) #0 of SFN #2.

In the second broadcast period 1012, the terminal may acquire a systemframe number and a subframe number. The terminal may determine whether asubsequent frame is an optimal beam (or a serving beam) of the terminal,that is, whether a decoding period arrives. The terminal may determinedecoding beams when the decoding period arrives. The terminal maydetermine decoding resources corresponding to decoding beams. Forexample, decoding resources may be symbols. The terminal may determinefour symbols. The terminal may determine a position on a time resourceof each of four symbols. Although a symbol is described as an example,the terminal may determine a position of a subframe number or framenumber in addition to symbol. The terminal may attempt decoding at adetermined position when the decoding period arrives.

The terminal may perform decoding in a period in which an optimal beamof the terminal is scheduled. The terminal may determine the secondframe 1022 as the decoding period. In the third broadcast period 1013and the fourth broadcast period 1014, the terminal may attempt decodingin decoding resources. The terminal may decode a system control signal.Depending on the position of the decoding resources acquired in aprevious broadcast period, the terminal may attempt decoding. Theterminal may reset the number of remaining decoding resources accordingto a decoding attempt result.

In the fifth broadcast period 1015, the terminal may process a decodingresult. If decoding is successful, the terminal may acquire systeminformation. For example, the terminal may acquire an MIB. The terminalmay acquire SIB1 on the basis of the MIB. The terminal may access a cellon the basis of the MIB and SIB1. Thereafter, the terminal may establishan RRC connection to the base station via a random access procedure andmay perform communication. If decoding fails, the terminal may wait.Thereafter, the terminal may determine decoding beams again to accessthe cell, and may attempt to acquire system information. For example,the terminal may wait until a subsequent optimal beam (beam #1) of theterminal is scheduled. The terminal may receive signals transmitted fromthe base station until the subsequent optimal beam of the terminal isscheduled, so as to update the decoding beams.

FIG. 10 illustrates an example in which a plurality of subframes arepresent in a frame, and a specific subframe includes a transmissionopportunity for a system control signal. However, the disclosure is notlimited to subframe-based transmission. According to variousembodiments, system control signals may be transmitted according toslot-based scheduling. For example, one frame may include at least oneslot. Each slot may include 14 symbols. A slot may include two systemcontrol signals (SS blocks). The number of slots in the frame may bechanged according to a configuration of SCS. The terminal may receivesystem control signals and may determine decoding beams, on the basis ofa resource structure determined according to the configuration of theSCS.

FIG. 5 to FIG. 10 describe a method for receiving, combining, anddecoding system control signals transmitted using different beams, so asto increase a probability of acquiring system information. As describedabove, in order to determine decoding beams for combined decoding andcombine signals, the terminal is required to store, compare, and managebeam-specific channel qualities. When a high frequency band issupported, the number of beams for covering a cell increases. When thenumber of pieces of information to be managed increases along with anincrease of the number of beams, a method for managing information foreach beam is additionally required.

Beam Information

FIG. 11 illustrates a flowchart of a terminal, for managing beaminformation according to various embodiments of the disclosure. Aterminal illustrates the terminal 120 of FIG. 1 . The terminal may storeand manage beam information for each beam to determine decoding beams.The terminal may store and manage beam information for each of beams(hereinafter, a system beam set) used when signals (e.g., an MIB and anSIB) including system information are transmitted. In FIG. 11 , anembodiment in which a system beam set includes four beams is described.Beams included in the system beam set may be referred to as decodingbeam candidates.

Referring to FIG. 11 , in operation 1101, the terminal may acquire abeam measurement result. The beam measurement result may be a channelquality for a beam. The terminal may measure a quality of a signaltransmitted using a specific beam in a specific time resource (e.g., asystem unit period) and may determine a channel quality. The terminalmay determine the channel quality for the specific beam. In a subsequentprocedure, the terminal may determine whether to store, as a decodingbeam candidate, the channel quality for the specific beam. A beam to besubject to determination of whether to be stored as a decoding beamcandidate may be referred to as a “target beam”.

In operation 1103, the terminal may determine whether a channel qualityof the target beam is lower than that of a fourth decoding beam. If thechannel quality of the target beam is lower than the channel quality ofthe fourth decoding beam, the terminal may perform operation 1105. Ifthe channel quality of the target beam is higher than the channelquality of the fourth decoding beam, the terminal may perform operation1107.

In operation 1105, the terminal may determine that the channel qualityof the target beam is not used as a decoding beam candidate. Theterminal may discard the channel quality of the target beam.

In operation 1107, the terminal may determine whether the channelquality of the target beam is equal to or higher than that of a firstdecoding beam. If the channel quality of the target beam is equal to orhigher than the channel quality of the first decoding beam, the terminalmay perform operation 1109. If the channel quality of the target beam islower than the channel quality of the first decoding beam, the terminalmay perform operation 1111.

In operation 1109, the terminal may replace the channel quality of thetarget beam and the second beam. Thereafter, the terminal may performrearrangement. The rearrangement may be performed between the existingfirst beam, a second beam, a third beam, and the fourth beam. Theterminal may perform rearrangement so that the second, third, and fourthbeams of the system beam set maintain a tree structure. After performingthe rearrangement, the terminal may exclude a beam having a lowestpriority from the system beam set. For example, the terminal may excludethe fourth beam. According to various embodiments, the terminal mayperform rearrangement by applying a priority queue algorithm. Theterminal may perform treeifying for rearrangement of the channelqualities or decoding beams of the beam set configured in a treestructure.

In operation 1111, the terminal may determine whether the channelquality of the target beam is equal to or higher than a channel qualityof the second decoding beam. If the channel quality of the target beamis equal to or higher than the channel quality of the second decodingbeam, the terminal may perform operation 1113. If the channel quality ofthe target beam is lower than the channel quality of the second decodingbeam, the terminal may perform operation 1115.

In operation 1113, the terminal may replace the channel quality of thetarget beam and the second beam. Thereafter, the terminal may performrearrangement. The terminal may perform rearrangement in the same manneras in operation 1109. According to an embodiment, the terminal may notinclude the first beam as an object to be rearranged.

In operation 1115, the terminal may determine whether the channelquality of the target beam is equal to or higher than a channel qualityof the third decoding beam. If the channel quality of the target beam isequal to or higher than the channel quality of the third decoding beam,the terminal may perform operation 1117. If the channel quality of thetarget beam is lower than the channel quality of the third decodingbeam, the terminal may perform operation 1119.

In operation 1117, the terminal may replace the channel quality of thetarget beam and the third beam. Thereafter, the terminal may performrearrangement. The terminal may perform rearrangement in the same manneras in operation 1109. According to an embodiment, the terminal may notinclude the first and second beams as objects to be rearranged.

In operation 1119, the terminal may replace the channel quality of thetarget beam and the fourth beam. The terminal manages up to 4 decodingbeams, and therefore additional rearrangement may not be performed.

In order to identify M decoding beams among N beams of the basestations, arrangement of measurement data (e.g., RSRP) for N beams maygenerally be preceded. By arranging N pieces of data and identifying Mbeams, the complexity of O(n²) or O(n·log n) may be required. That is,in order to determine a plurality of decoding beams, if decoding isperformed in each broadcast period and rearrangement is performed forall beams, it may act as a burden on processing of the terminal. Aprocessing time varies according to the number of beams of the basestation, and an unexpected delay may thus occur. Therefore, asillustrated in FIG. 11 , the complexity may be reduced by maintainingupper M number of beams via simple comparison. In addition, the terminaldoes not perform rearrangement of data for all beams, and it may thus bepossible to efficiently store, identify, and manage M beams within aconstant time.

FIG. 12 illustrates an example of managing beam information according tovarious embodiments of the disclosure. A terminal may include a database(DB) for beam information to manage the beam information. The databasemay include a system beam set 1210. As shown in FIG. 11 , an embodimentin which the system beam set includes four beams is described.

Referring to FIG. 12 , the system beam set 1210 may include a firstchannel quality 1211 of a first beam having a highest channel quality, asecond channel quality 1212 of a second beam having a second highestchannel quality, a third channel quality 1213 of a third beam having athird highest channel quality, and a fourth channel quality 1214 of afourth beam having a fourth highest channel quality.

The terminal may measure a quality of a signal each time when the signalis transmitted via a different beam of the base station, and maydetermine a channel quality for the corresponding beam. The terminal maydetermine a first channel quality 1220 for a target beam (x). That is,the terminal may newly acquire data for the first channel quality 1220.The terminal may compare the acquired new data with data for beams of anexisting system beam set. According to various embodiments, as describedin FIG. 11 , the terminal may first compare the newly acquired data witha channel quality of a beam having a lowest priority, and then maysequentially perform comparison with a beam having a highest priority.For example, the terminal may first compare a channel quality of thetarget beam with a channel quality of a fourth beam 1214, and then maycompare channel qualities of beams in the order of a first beam 1211, asecond beam 1212, and a third beam 1213. If it is determined that thechannel quality of the target beam is higher than that of a specificbeam in the beams of the system beam set, the terminal may replace thetarget beam and the specific beam. The terminal may no longer performcomparison and may rearrange the system beam set.

The terminal may determine a second channel quality 1221 for a targetbeam (Y). Like beam X, the terminal may compare the second channelquality 1221 with each of the channel qualities of the beams in thesystem beam set. The terminal may determine a third channel quality 1222for a target beam (Z). Like beam X or beam Y, the terminal may comparethe third channel quality 1222 with each of the channel qualities of thebeams in the system beam set. That is, the terminal may determine thechannel quality for the target beam each time when a beamforming signalis received. The terminal may compare the channel quality for the targetbeam with each of the channel qualities of the beams of the system beamset.

In FIG. 11 and FIG. 12 , an example of managing four decoding beams as asystem beam set has been described, but the disclosure is not limitedthereto. The terminal may store fewer than 4 decoding beams or more than4 decoding beams in the system beam set in order to acquire systeminformation.

The terminal may store not only a channel quality for each beam of thesystem beam set, but also resource information related to the beam. Bystoring the resource information, the terminal may easily identify aresource position of a signal transmitted using the corresponding beamin a broadcast period. That is, the terminal may identify the beam onthe basis of the resource information. The resource informationindicating a beam in this manner may be referred to as a resourceindicator. Hereinafter, FIG. 13 describes a method for storing, by aterminal, resource information associated with each beam of a systembeam set.

Resource Information

FIG. 13 illustrates an example of resource information related to a beamaccording to various embodiments of the disclosure. Here, a beam is fora system control signal of a terminal, and may be a decoding beam thatis to be decoded. The terminal may store resource information for thedecoding beam.

Referring to FIG. 13 , the terminal may store resource information in ahierarchical structure form on each resource. According to variousembodiments, the resource information may include a first parameter1301, a second parameter 1303, a third parameter 1305, a fourthparameter 1307, and a fifth parameter 1309. The first parameter 1301 mayrefer to a frame number. That is, the first parameter 1301 may be SFN.The second parameter 1303 may refer to a subframe number. The thirdparameter 1305 may refer to the number of symbols. Each of the fourthparameter 1307 and the fifth parameter 1309 may refer to a symbol index.

A situation, in which a base station transmits a system control signalby using each of a predetermined number of beams every 5 ms, isdescribed as an example. The first parameter 1301 may refer to a framenumber. A broadcast period exists in each frame, and therefore the firstparameter 1301 may include SFNs. The terminal may store SFNs inascending order increasing by one. The second parameter 1302 may referto a subframe number. A 0th subframe and a 25th subframe may bebroadcast periods. The second parameter 1302 may indicate 0 and 25.

Due to characteristics of a communication system, decoding may beattempted and combination may be performed in more than one symbol evenwithin one subframe. Accordingly, the terminal may store the number ofsymbols in the third parameter 1305. If the number of decoding beams is2 in one subframe, the terminal may store, as 2, a value of the thirdparameter 1305. Depending on the value of the third parameter 1305, thenumber of subsequent parameters may be determined. If the thirdparameter 1305 is 2, the terminal may include the fourth parameter 1307and the fifth parameter 1309.

The fourth parameter 1307 may indicate an index of a symbolcorresponding to a decoding beam. A subframe may include 14 symbols. Thefourth parameter 1307 may be one of 0 to 13. The fifth parameter 1309may indicate an index of a symbol corresponding to another decodingbeam. The fifth parameter 1309 may be one of 0 to 13.

In FIG. 13 , resource information is described on the basis of acommunication system in which one frame includes 50 subframes and systemcontrol signals are transmitted in two subframes. However, thedisclosure is not limited thereto. The terminal may include resourceinformation based on another resource structure. According to anembodiment, the resource information may further include parametersindicating a slot, the number of slots, and a half frame.

According to various embodiments, the terminal may use resourceinformation to determine whether beams of a system beam set arescheduled in a broadcast period or a decoding period. That is, theterminal may use resource information to determine whether the basestation transmits system control signals by using the beams of thesystem beam set. The terminal may attempt to decode the system controlsignals transmitted using the beams of the system beam set, on decodingresources of the resource information.

As described in FIG. 5 to FIG. 13 , the terminal according to variousembodiments of the disclosure may acquire beam diversity bycombined-decoding system control signals transmitted using differentbeams. Specifically, the performance for successfully acquiring systeminformation may be improved by receiving signals also in other beams andperforming decoding via an LLR combination, as well as performingdecoding to acquire the system information only in a single optimalbeam. When the number of combinations increases, a reception gain mayincrease by about 3 dB.

Combined decoding according to various embodiments provides animprovement in reception performance. Whether to perform combineddecoding of the disclosure may be determined by measuring the receptionperformance in a weak electric field (−100 dBm or −110 dBm) andconfirming that the reception gain is increased. According to variousembodiments, whether to perform combined decoding of the disclosure maybe determined based on whether the terminal performs decoding in anotherbeam in addition to a specific beam within a broadcast period in whichsystem information is transmitted. For example, the terminal may attemptdecoding on a resource different from a resource that is fed back to thebase station within the same broadcast period.

Although the disclosure has been described based on a situation in whicha base station broadcasts system information, the disclosure may also beapplied to a situation in which the base station repeatedly transmitsnot only system information but also base station-specific orcell-specific parameters by sweeping beams. In addition, embodiments ofthe disclosure may also be applied to a situation in which a terminalreceives data (e.g., PDSCH) transmitted using at least two beams (e.g.,CRIs or SSBRIs) of a base station.

In the disclosure, the expression “equal to or greater than” or “equalto or less than” is used to determine whether a specific condition issatisfied (fulfilled), but this is merely a description to represent anexample and does not exclude “exceeding” or “less than”. For example, acondition described as “equal to or more than” may be replaced by“exceeding”, a condition described as “equal to or less/fewer than” maybe replaced by “less/fewer than”, a condition described as “exceeding”may be replaced by “equal to or more than”, a condition described as“less/fewer than” may be replaced by “equal to or less/fewer than”, acondition described as “equal to or more than, and less/fewer than” maybe replaced by “exceeding, and equal to or less/fewer than”, and acondition described as “exceeding, and equal to or less/fewer than” maybe replaced by “equal to or more than, and less/fewer than”.

Methods disclosed in the claims and/or methods according to variousembodiments described in the specification of the disclosure may beimplemented by hardware, software, or a combination of hardware andsoftware.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program may includeinstructions that cause the electronic device to perform the methodsaccording to various embodiments of the disclosure as defined by theappended claims and/or disclosed herein.

The programs (software modules or software) may be stored in nonvolatilememories including a random access memory and a flash memory, a readonly memory (ROM), an electrically erasable programmable read onlymemory (EEPROM), a magnetic disc storage device, a compact disc-ROM(CD-ROM), digital versatile discs (DVDs), or other type optical storagedevices, or a magnetic cassette. Alternatively, any combination of someor all of them may form a memory in which the program is stored.Further, a plurality of such memories may be included in the electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich may access the electronic device through communication networkssuch as the Internet, Intranet, Local Area Network (LAN), Wide LAN(WLAN), and Storage Area Network (SAN) or a combination thereof. Such astorage device may access the electronic device via an external port.Further, a separate storage device on the communication network mayaccess a portable electronic device.

In the above-described detailed embodiments of the disclosure, anelement included in the disclosure is expressed in the singular or theplural according to presented detailed embodiments. However, thesingular form or plural form is selected appropriately to the presentedsituation for the convenience of description, and the disclosure is notlimited by elements expressed in the singular or the plural. Therefore,either an element expressed in the plural may also include a singleelement or an element expressed in the singular may also includemultiple elements.

Although specific embodiments have been described in the detaileddescription of the disclosure, modifications and changes may be madethereto without departing from the scope of the disclosure. Therefore,the scope of the disclosure should not be defined as being limited tothe embodiments, but should be defined by the appended claims andequivalents thereof

The invention claimed is:
 1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, a first synchronization signal (SS) block, which is transmitted using a first beam of the base station, wherein the first SS block includes system information; receiving, from the base station, a second SS block, which is transmitted using a second beam of the base station, wherein the second SS block includes the system information; and acquiring the system information by decoding the second SS block in combination with the first SS block based on first probability information of the first SS block and second probability information of the second SS block.
 2. The method of claim 1, wherein each of the first probability information and the second probability information comprises LLR (log likelihood ratio), and wherein the LLR indicates whether each value of bits of a SS block including the first SS block and the second SS block is 1 or not.
 3. The method of claim 2, the method further comprising: determining a first vector corresponding to the first probability information of the first SS block based on detection of the first SS block; and determining a second vector corresponding to the second probability information of the second SS block based on detection of the second SS block.
 4. The method of claim 1, wherein the first SS block is modulated based on a modulation scheme, and wherein the second SS block is modulated based on the modulation scheme.
 5. The method of claim 1, wherein the system information is at least of parameters of a system information block (SIB) or a master information block (MIB).
 6. The method of claim 1, wherein the acquiring of the system information comprises: acquiring combined probability information for the system information based on the first probability information and the second probability information.
 7. The method of claim 1, wherein the acquiring of the system information comprises performing the decoding by applying a first weight to the first SS block and applying a second weight to the second SS block, and wherein the first weight and the second weight are determined based on a first channel quality for the first SS block and a second channel quality for the second SS block.
 8. The method of claim 1, wherein the acquiring of the system information comprises: decoding the second SS block in combination with the first SS block in response to detection of a failure of decoding the first SS block.
 9. The method of claim 1, wherein a number of combined SS blocks for the system information is determined based on a time duration for the system information or a capability of the terminal.
 10. The method of claim 1, wherein the first SS block includes a first index associated with the first beam, and wherein the second SS block includes a second index associated with the second beam.
 11. A terminal in a wireless communication system, comprising: a transceiver; and at least one processor coupled with the transceiver, wherein the at least one processor is configured to: receive, from a base station, a first synchronization signal (SS) block, which is transmitted using a first beam of the base station, wherein the first SS block includes system information, receive, from the base station, a second SS block, which is transmitted using a second beam of the base station, wherein the second SS block includes the system information, and acquire the system information by decoding the second SS block in combination with the first SS block based on first probability information of the first SS block and second probability information of the second SS block.
 12. The terminal of claim 11, wherein each of the first probability information and the second probability information comprises LLR (log likelihood ratio), and wherein the LLR indicates whether each value of bits of a SS block including the first SS block and the second SS block is 1 or not.
 13. The terminal of claim 12, wherein the at least one processor is further configured to: determine a first vector corresponding to the first probability information of the first SS block based on detection of the first SS block, and determine a second vector corresponding to the second probability information of the second SS block based on detection of the second SS block.
 14. The terminal of claim 11, wherein the first SS block is modulated based on a modulation scheme, and wherein the second SS block is modulated based on the modulation scheme.
 15. The terminal of claim 11, wherein the system information is at least of parameters of a system information block (SIB) or a master information block (MIB).
 16. The terminal of claim 11, wherein the at least one processor is further configured to: acquire combined probability information for the system information based on the first probability information and the second probability information.
 17. The terminal of claim 11, wherein the at least one processor is further configured to perform the decoding by applying a first weight to the first SS block and applying a second weight to the second SS block, and wherein the first weight and the second weight are determined based on a first channel quality for the first SS block and a second channel quality for the second SS block.
 18. The terminal of claim 11, wherein the at least one processor is further configured to: decode the second SS block in combination with the first SS block in response to detection of a failure of decoding the first SS block.
 19. The terminal of claim 11, wherein a number of combined SS blocks for the system information is determined based on a time duration for the system information or a capability of the terminal.
 20. The terminal of claim 11, wherein the first SS block includes a first index associated with the first beam, and wherein the second SS block includes a second index associated with the second beam. 